It's easier said then done, but try some of the little things that make many people feel happier and more confident:

Go take a walk around midtown, or Capitol Park, or McKinley Park (maybe not during this heat wave)...you will pass by a lot of people and it tends to cheer you up to be around others doing a similar activity. Smile at anyone as you walk by, make some eye contact, sometimes a casual "hello" or "good morning".

Every time you interact with someone in public be friendly and offer a smile and eye contact. This can be the checkout clerk at the grocery store, the coffee shop barista, the car wash attendant...it doesn't take much, just a little eye contact and smiling and you'll be surprised at the confidence and connections it seems to build.

Don't underestimate the power of nutrition and exercise. Do a little research on basic nutrition and basic exercise, and force yourself to improve those. Once you get in a routine, your body will feel immensely better and you will gain confidence like you never imagined.

I seriously can't over emphasize the power of eye contact with strangers, smiles, nutrition, and exercise. It's always hard to start, but it's never too late to start and there's never too small a first step to take.